We propose to further study the alterations of the voltage dependent sodium and potassium conductances as a function of internal pH. In addition, we are going to study the effects of certain reagents which alter the chemical nature of specific amino acid residue. Among these reagents we are going to study cross-linking compounds such as glutaraldehyde. Another group of experiments will investigate the effect of changing the lipid composition of the giant axon using a liposome technique. BIBLIOGRAPHIC REFERENCES: Brown, A.M., M.S. Brodwick and D.C. Eaton. Intracellular calcium and extra-retinal photoreception in Aplysia giant neurons. J. Neurobiol. 8(1): 1-18. Russell, J.M., D.C. Eaton and M.S. Brodwick. 1977. Effects of nystatin on membrane conductance and internal ion activities in Aplysia neurons. J. Memb. Biol. (in press).